| 摘要 |
PURPOSE:To prevent the generation of track deviation by obtaining a false error signal approximating the error signal of a running track and using this false error signal for the time when a tracking information signal is dropped out. CONSTITUTION:Drop-out of the tracking information signal is detected in a drop- out detecting circuit 11 on a basis of one of tracking information and another signal which is detected in relation to this tracking information. Low frequency components of the tracking error signal detected by an error detector 2 are denoted as X input, and the operation of (1/a)X+(1/b)Y, where (a) and (b) are so set that the condition of (1/a).[1/(b-1)]=1 is satisfied when a>1 and b>1 are true, in the relation to Y input is executed in a means 10, and this operation result is delayed in a delay circuit 8 by a time corresponding to one rotation of the recording track to generate Y input. When drop-out is detected, the delayed output is switched in a switch 12 and is supplied to a tracking control driving system 4 instead of the tracking error signal. |
